All living organisms organize their DNA into chromosomes; this is a common characteristic.
Each species has a specific number of chromosomes:
Humans: 46 chromosomes
Watermelon: 22 chromosomes
Goats: 60 chromosomes
The number of chromosomes does not correlate with the complexity of the organism.
Evolution from a Common Ancestor
Chromosome Variation Theory:
Evolutionary biology proposes that different species can retain unique chromosome numbers.
Hypothetical scenario: an organism starts with 2 chromosomes. If a chromosome gets separated, this could lead to species evolving with different chromosome counts over time.
Karyograms and Karyotypes
Understanding Karyograms:
A karyogram is a pictorial representation of an organism's chromosomes.
Karyotype: characteristics of chromosomes in a species based on the karyogram.
Human karyogram appears with 46 chromosomes, often analyzing males with X and Y chromosomes.
Creating Karyotypes:
Cell Selection: Identify a cell in mitosis.
Staining Cells: Use stains that attach to DNA.
Cell Lysis: Burst the cell to analyze chromosomes.
Organization: Arrange chromosomes based on centromere position and size.
Definitions in Genetics
Genome:
Complete set of genetic information in an organism, consisting of all base sequences (A, T, G, C).
Gene:
Segment of DNA that encodes for a protein (e.g., a gene for blood type).
Unity in Species:
Organisms of the same species have the same genes in the same chromosome locations.
Diversity within Species:
Variation in alleles (different base sequences) for the same gene among individuals of a species.
Single Nucleotide Polymorphisms (SNPs):
Positions in DNA where individuals may differ in a single nucleotide, responsible for variation in traits.
Approximately 5,000 SNPs among 3 billion base pairs in human DNA.
Comparison of Genetic Information
Diversity Across Organisms:
Two different organisms, such as goats and apples, can exhibit significant differences:
Different genome sizes or numbers of genes.
Variations in base sequences within identical genes.
Quantifying Genome Size:
Methods to quantify genome size:
By mass (not practical due to small DNA mass, e.g., humans: 6 picograms)
By number of base pairs (e.g. humans: 3,200,000,000,000 base pairs)
Advances in Genomic Sequencing
Evolutionary Relationships and Sequencing:
Genome sequencing has improved significantly, enabling faster and cheaper analysis of different organisms.
This advancement can modify our understanding of evolutionary relationships, potentially changing previous classifications.
Applications of Genomic Knowledge:
Can contribute to personalized medicine and understanding diseases based on genetic information.
Identifying how different genes influence drug effectiveness, such as pain medication.
Potential for Future Discovery:
Ongoing genomic research presents opportunities for innovative applications and insights in biology, healthcare, and beyond.